1. Field of the Invention
The present invention relates to an elevator car door interlock.
2. Description of the Related Art
Several designs for elevator car door restrictors have been designed in the past. Many commercially available elevator systems have car door interlocks that require the use of rigidly mounted flags (flags are rigid structures affixed to the sides of the hoistway) along the entire length of the hoistway with predetermined interruptions. None of them, however, include the use of flags to allow the elevator car doors to open. The flags are used to keep the elevator car doors closed except when interrupted in registration with the landings.
A door locking system is disclosed in EP 1,886,963. This system includes the use of a door interlock assembly (16) in each landing (Par. 20). This European reference disclosed a complicated mechanism that requires the use of at least one interlock assembly (16) at each landing.
Alternative elevator car door interlocks rely on the elevator's clutch with several moving parts, which uses pick up rollers. Relying on these rubber pick up rollers is unreliable because they include many small moving parts and are made of rubber, both are easily vulnerable to wear and tear. This requires significant maintenance. The lack of such maintenance typically leads to elevator code violations or breakdowns. Also, these types of restrictors require precise adjustments for them to work, as they require a straight path throughout the hoistway. The present invention can work independently of any clutch that is used and does not rely on the clutch for the restrictor to work. This means that even if the clutch requires maintenance there will not be a violation for a faulty restrictor because the restrictor works independently from the clutch. In addition, the present invention is adjustable and can readily conform to a hoistway that is not entirely straight.
Other designs for elevator car door restrictors include a bar system that is mounted to the inner elevator car door. With these designs the car doors are allowed to open at any portion throughout areas where there are no flags along the hoistway. Thus, numerous flags are required along the hoistway to keep the elevator doors locked. This leads to an added cost in elevator installations and increases the likelihood of a failure due to there being more parts that may fail. Additionally, the bar system makes it more difficult for emergency personnel to open the car doors in case of an emergency because of the challenges associated with reaching the remote bar.
Moreover, the nature of bar system requires the flags that the bar pushes up against to withstand the force of the elevator doors wanting to open. This force requires that the flags be made out of a heavier—and more costly—material. Also, if there are recesses along the hoistway, fascia must be installed to fill the space so that the flag can reach the bar system. This is yet another added expense related to the bar system.